Full-freedom gimballess gyroscope system

ABSTRACT

A gyroscope system having a gyro rotor completely enclosed within a spherical float that is supported within a hollow spherical cavity by a flotation fluid and a spherical arrangement of hydrostatic bearing pads. The gyroscope rotor is mounted on a spin axle by a duplex bearing arrangement to be spun by a motor also within the float. A set of orthogonally arranges sensing coils are mounted within the spherical cavity to surround the float. Flux emanating from magnetic pole pieces carried on the rotor cut the coil windings to generate output signals, the relative amplitude and phasing of which is indicative of the angular displacement of the rotor spin axis from each of the coil axes. A caging mechanism maintains the float in an initial position and may be used to supply power from an external source to accelerate the spin motor. After uncaging, spin motor power is supplied either from batteries carried within the float or from an external source which supplies power through a capacitive or conductive coupling between the conductive surface of the hydrostatic bearing pads and adjacent circular conductive segments at either end of the float.

United States [72] Inventor Richard B. Clark [54] F ULL-FREEDOMGIMBALLESS GYROSCOIPE [56] References Cited UN lTED STATES PATENTS3,199,932 8/1965 Clark 74/5 X 3,262,324 7/1966 Taylor 74/5 PrimaryExaminer-Verlin R. Pendegrass Au0rneyDonald E. Nist ABSTRACT: Agyroscope system having a gyro rotor completely enclosed within aspherical float that is supported within a hollow spherical cavity by aflotation fluid and a spherical arrangement of hydrostatic bearing pads.The gyroscope rotor is mounted on a spin .axle by a duplex bearingarrangement to be spun by a motor also within the float. A set oforthogonally arranges sensing coils are mounted within the sphericalcavity to surround the float. Flux emanating from magnetic pole piecescarried on the rotor cut the coil windings to generate output signals,the relative amplitude and phasing of which is indicative of the angulardisplacement of the rotor spin axis from each of the coil axes. A cagingmechanism maintains the float in an initial position and may be used tosupply power from an external source to accelerate the spin motor. Afteruncaging, spin motor power is supplied either from batteries carriedwithin the float or from an external source which supplies power througha capacitive or conductive coupling between the conductive surface ofthe hydrostatic bearing pads and adjacent circular conductive segmentsat either end of the float.

PATENTEU nus 3191s SHEET 1 [1F 6 I W F INVENTOR. RICHARD H. CLARK FraserDogma/(1' ATTORNEYS PMENIEDAUQ 3:971 3596.523

SHEET 2 BF 6 INVENTOR. RICHARD B. GLMIK o 2 X Fr se at.

A TTORNEYS PMENTEMUE 3m 3,596,523

sum 3 OF 6 am w AUDI to O? o N VENT RlCHARD B. CLARK w m Fraser B y/ck iA TTO R N E Y3 PATENTED Mn; 3 m

SHEU b 0F T0 COMMUTATOR CIRCUITS 244 INVENTOR. mum B. cum

Wa er fio uck;

A TORNEYS PMENTEU mm men 3,596; 523

sum s or 6 PHASE DETECTOR ANALOG SIGNAL AND ALYZER COMPARATOR ANGLECIRCUITS RESQLVER W W W W M ITUDE ORTHOGONAL W COMPUTER VECTOR SIGNALOUTPUTS T0 254 OR 256 W PHASE gl J l NTATmN ATTITUDE CONTROLS REFERENCECOMPUTER COMPUTER INVENTOR.

RICHARD B. CLARK FY2567 Bo ucKi ATTORNEYS PITCH f SIGNAL PATENTEUAUG3L9?! 3,596,523

SHEET 0F 6 PHOTOCELL PHOTOCELL cmcun cmcurr mo 242 M4 244 I52 7 2 emuemu) mum BRIDGE 24o cmcurr cmcun PHOTOGELL [74PHOTOCELL cmcurr omcun'INVENTOR. 1W5 CQNMHQMER RICHARD B. CLARK BY y 1 Fraser BqyvcK PITCH YAWROLL ATTORNEYS BACKGROUND OF THE lNVENTlON Gyroscopes are extensivelyused in a variety of applications for attitude reference andnavigational systems in all types of vehicles, particularly aircraft,rocltet vehicles and the lilte. Conventionally gimbaled gyroscopes,however, suffer from certain inherent limitations in their ability toprovide accurate attitude reference under conditions resulting from thepresent trend towards extremely high accelerations and maneuverability.

Random drift of the spin axis in conventional gyros is primarily theresult of gimbal bearing friction and constitutes the most serioussource of attitude error in conventional gyros. Coulomb friction betweensolid bearing surfaces in most conventional gimbal systems malres thisrandom drift wholly unpredictable. bearing friction problems are furtheraggravated under high accelerations] conditions, and most conventionallow friction girnbal bearings would either be degraded or severelydamaged by accelerational environments of more than l g's presentlycontemplated in some applica tions.

Previously, liquid flotation systems have been employed to reducebearing friction in high accelerational environments by reducing weightloads on the gimbals. However, although such flotation systemssignificantly reduce friction loads on the gimbal bearings, eliminationof the problem is not possible due to precession torques and chancecontact even though perfect flotation under all temperature andaccelerational conditions is maintained.

ln addition, conventional, two degree of freedom gyros are also subjectto the condition commonly lrnown as gimbal loclt. To avoid gimbal lochand the resulting possibility of uncontrolled tumbling, either thefreedom of the gyro must be limited or a third gimbal must be addedalong with complex controls and picltoffs. However, the third gimbalgreatly increases system complexity and constitutes yet another sourceof errors.

To avoid problems of bearing friction, some gyroscope systems have beendeveloped to operate completely without gimbals. ln such systems thegyroscope rotor is supported for free rotation either by a gas-bearingor by electrostatic or magnetic force fields. Typically the rotor isdriven by an eddy current motor through inductive coupling on theconductive rim of the rotor. However, the attitude response of suchprevious gimballess systems has been severely limited because the rotorhad to remain in substantially the same alignment with the externaldrive means and the pichoff system used to sense gyro attitude was onlycapable of measuring small angular displacements. Gas-bearing,electrostatic and magnetic gyro support systems are not suitable wherevery high accelerations and unlimited maneuverability are required sincethe forces needed to support the rotor are beyond the practicalcapabilities of such systems.

hitllElF SUMMARY 01F Tll-llE lNVENTlON This invention provides a trulyfull-freedom gyro system that is substantially free ofacceleration-sensitive drift and attitude limitations, and is capable ofoperating with unlimited maneuverability even in high accelerationalenvironments.

The rotor and spin motor are completely enclosed within a sealedspherical float which is supported by a liquid medium within a sphericalcavity. The gyro spin motor is powered from a supply means containedwithin the float thus requiring no external physical interconnection tothe spherical shell about the float. An inductance-type picltoffarrangement, consisting of three orthogonally oriented, circular sensingcoils arranged about the spherical cavity, respond to a rotatingmagnetic pole carried on the rotor to generate output signals indicativeof the float attitude within the cavity with respect to the sensing coilorientation. The gyroscope rotor is thus supported by the float withfull attitude freedom within the spherical cavity, and the picltoffarrangement is capable of precisely sensing an unlimited range ofattitude angles.

The system also includes a caging mechanism for engaging the float tomaintain a desired initial attitude alignment and hold the float againstrotation during runup until the rotor has achieved the desired spinrate. The caging mechanism includes a plurality of pins that areinserted through the cavity into receptacles in the float to supplyelectrical power from an external source to the spin motor during runup.After the rotor has been accelerated to the desired spin rate, the pinsare withdrawn to give the float full attitude freedom within the cavity.Thereafter the reduced power requirements of the spin motor needed formaintaining the spin rate are supplied either by storage batteriescarried within the spherical float itself or by an extemal source to thefloat through conductive or capacitive couplings across the fluidsurrounding the float in the cavity.

in an exemplary form of the invention, the spherical shell of the floatassembly is supported within the spherical cavity by an arrangement ofhydrostatic bearings. Each hydrostatic bearing pad is shaped to fit oneof the spherical segments defined between the orthogonally disposedsensing coils. The hydrostatic bearings preserve the free attituderesponse to the spherical float even under the most severe maneuveringand accelerational conditions, and the arrangement of bearing padsprovides a convenient means for transferring electrical power from anexternal source to the spin motor within the float to either supplementor replace that obtained from battery cells carried within the floatitself. For this purpose, the surface of the float may be provided withtwo conductive cir' cular portions on opposite ends of the float, eachcovering an area approximating the area covered by one of thehydrostatic bearings formed of a conductive material. Small amounts ofpower needed to sustain the spin rate can then be transferred to theconductive areas on opposite ends of the float from the pair of closelyadjacent bearing pads opposite each end. Using a nonconductive flotationfluid, high frequency alternating electrical power can be transmittedthrough the capacitive coupling established between the conductive areason the float and the adjacent bearing pads, and this alternating signalcan either be rectified to run the DC spin motor or reduced in frequencyto run an appropriate AC motor. Alternatively, using a suitableconductive fluid, DC power can be transferred across the narrow gapbetween the conductive areas on the float and the oppositely disposedbearing pads.

Preferably, the rotor is driven by a DC spin motor which has a permanentmagnet carried on the rotor for rotation about a plurality of statorwindings. The rotor is journaled for rotation at the center of the floatby duplex bearings disposed at either end so that under allaccelerational conditions the load is shared by a bearing at each end.To eliminate additional power requirements and loose metal fragments, abrushless DC spin motor is preferred of the type employing opticalshutters on the rotor to gate light to photocells on the stator whichdistribute current flow in the appropriate direction through the statorwindings. I

Magnetic pole pieces carried by the rotor provide pole tips of oppositepolarity at the rotor periphery. As the rotor spins, flux from the tipsof the pole pieces on opposite sides cut the windings of the sensingcoils to generate output signals having amplitude and phasecharacteristics indicative of the angular displacement of the spin axisfrom the sensing axis of each coil. The amplitude of the output signalfrom any given coil corresponds to the cosine of the angle between theplane of the coil and the spin axis, and the relative phase relationshipbetween the output signals from the three coils is uniquely indicativeof the spin axis alignment relative to the orthogonal alignment of thecoils. In addition, the sensing coils can be employed in erecting orrestoring the gyro to a desired initial alignment merely be shorting thecoil whose sensitive axis corresponds to the desired spin axis alignmentor by applying an appropriate erecting signal to the coil.

As another aspect of the present invention, an all-attitude referencesystem, or stable platform, may be provided by mounting two of thedescribed gyros on a suitable support with the spin axes of the gyrosinitially set in a known angular relation, such as at right angles, toone another. A signal conditioning or computer means, in response to thepickoff outputs, furnishes the desired attitude signals with respect toa three dimensional reference coordinate system. Mounted in a vehicle,having orthogonal pitch, yaw and roll axes, and with the spin axis ofone of the gyros initially parallel to the pitch axis and the spin axisof the other gyros parallel to the yaw axis, for example, this referencesystem provides complete attitude information for any vehicleorientation in terms of vehicle coordinates.

BRIEF DESCRIPTION OF THE DRAWINGS Objects and advantages other thanthose indicated above will be apparent from the Detailed Description,below, when read in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of the exterior of a gyroscope systemaccording to the present invention;

FIG. 2 is a composite section view of the gyroscope system of FIG. 1taken along 2-2;

FIG. 3 is a section view of a float according to the present inventionfor use in the gyroscope system of FIGS. 1 and 2;

FIG. 4 is a perspective, schematic view of an array of hydrostaticbearing pads utilized in the gyroscope system of the present invention;

FIG. 5 is a section view of the float of FIG. 3 taken along the plane5-5;

FIG. 6 is a section view of the float of FIG. 3 taken alone the plane6-6;

FIG. 7 is a section view of the float of FIG. 3 taken along the plane7-7;

FIG. 8 is a section view of the float of FIG. 3 taken along the plane8-8;

FIG. 9. is a section view of the float of FIG. 3 taken along the plane9-9;

FIG. 10 is a schematic representation of a portion of the gyroscopesystem of the present invention along with a schematic of an associatedelectrical battery charging and motor drive circuit;

FIG. 10A is a schematic of an alternative form of power supply circuitwhich provides positive speed control of the gyro motor;

FIG. 11 is a schematic and block representation of the pickoff system ofthe present invention;

FIG. 12 is a partial sectional view of a float shell for use in analternative embodiment of the present invention;

FIG. 13 is a schematic and block representation of a motor currentsupply system used in connection with the alternative embodimentemploying the float shell of FIG. 12;

FIG. 14 is a schematic of a circuit used in connection with thealternative embodiment of FIGS. 12 and I3;

FIG. I5 is a partial schematic representation of an altemative circuitfor driving an AC rotor drive motor; and

FIG. 16 is a schematic, perspective view of an all-attitude referencesystem employing two gyroscope systems of the present invention.

DETAILED DESCRIPTION Referring to FIGS. 1 and 2, a gyro system 10,according to one form of the present invention, is shown which includesa tubular outer housing 12 enclosing a pair of cylindrical bodies 14 and16 which between them define an internal space 18. The bodies 14 and 16are held in place by end plates 20 and 22 secured to the outer housing12 by a series of screws 24 and sealed by O-rings 25. Supported withinthe space 18 is a pair of generally hemispherical structures 26 and 28which define a substantially spherical, fluidtype cavity 30. Thehemispheres 26 and 28 are provided with mating flanges 32 joinedtogether by appropriate fastening means, such as bolts 34, and clamponring 36.

The gyro system described thus far may be conveniently related to anarbitrary coordinate system consisting of mutually orthogonal axes'XX,YY and 22, which define planes XY, X2, and YZ. The housing 12 isconcentric with the longitudinal axis XX, and the geometric center ofthe spherical cavity 30 coincides with the origin 0. Axis YY may beviewed as the lateral axis and axis ZZ the vertical axis.

A spherical float 40, to be described in detail later, ishydrostatically suspended within the cavity 30. Specifically, in theembodiment shown, the float 40 is supported within the cavity 30 by asymmetrical arrangement of eight hydrostatic bearing pads 42 mounted inrecesses 44 in the walls of the hemisphere structures 26 and 28. Eachpad 42 is attached to the hemisphere 26 or 28 by a bolt 49 that engagesthreads provided on a backward extension. Three or more pad adjustmentscrews 50 extended through the body of the hemisphere structures 26 and28 contact the rear of each bearing pad 42 to permit minute tiltingadjustments of the pad 42 so that a uniform gap will exist (in theabsence of extraneous disturbing forces on the float) between the face46b and the outer surface of the float 40. The central area of each padface 46 is provided with a depression 46a leaving a surrounding, raisedmargin 46b of substantially constant width. Fluid introduced into thegap around the float under pressure through an inlet orifice 52 in thecenter of each pad face 46 flows outwardly across the depression 46a andover the raised margin 46b to form the hydrostatic bearing. The 46atemporarily contains a larger volume of fluid than would be present ifthe face 46 were smooth thereby reducing viscous drag and increasing thearea over which the pressure acts. Typically, the gap between the outersurface of the float 40 and the depressed central area 46a of the padface 46, for a 2.5 inch diameter float is approximately 0.020 inch withthe gap at the raised margin 46b approximately 0.003 inch. A resilientgasket 54 is seated within a peripheral step 56 in the rear face of eachpad 42 to provide a fluidtight seal around the edge of the pad.

A positive displacement pump such as gear pump 60, mounted in a cavityin the body member 16 and driven by suitable motor means (not shown),delivers the fluid to the bearing pads 42 at a substantially constantrate through a manifold arrangement comprising passages 62, formed inthe body members 14 and 16, and communicating with the inlet orifices52. Fluid from the cavity 30 drains through an outlet 64 back to theinlet of the gear pump 60 via a return conduit 66. A constant amount offluid sufficient to fill the fluid system, at least within the sphericalcavity, is continuously recirculated by the pump 60. Changes in thevolume of the fluid or in the fluid capacity of the system due toambient temperature variations may be handled either by closelyregulating system temperature at a constant level, which is in any casedesirable, or by providing a suitable reservoir to compensate forexpansion or contraction. As shown in FIGS. 1 and 2, a reservoir cavity68 surrounds a flexible bellows 70 containing air or other compressiblegas and is connected via a fluid passage 72 to the spherical cavity 30to provide a variable volume which expands and contracts with variationsin the fluid capacity within the the cavity. With the bellow 70 locatedforward of the float cavity 30 with respect to the directions ofacceleration, the fluid is introduced into the cavity 68 under pressureto compress the bellows so that it maintains a preload pressuresufficient to prevent bubble formation under the highest accelerationalforces, since sudden movements of fluid to displace bubbles couldgenerate unbalanced fluid friction forces on the float surface. In theexample of FIGS. 1 and 2, the bellows 70 is oriented along thelongitudinal axis XX with positive acceleration forces acting primarilyin a direction parallel to the axis XX as indicated by the arrowdesignated +g".

The density of the hydrostatic bearing fluid should provide preciseflotation of the float 40 within the spherical cavity 30 and should havea relatively low viscosity to minimize the effects of viscous drag onthe float. Obviously, the more dense the fluid, the heavier the floatstructure may he, and thus the more weight, particularly in. batterycells, which may be carried within the float. Although most high densityfluids also tend to have high viscosity, lubricating fluids withsuitably low viscosity for this application are readily available withdensities in excess of 1.8 g./cc. ideal fluids for this purpose areprovided by lubricating liquids, such as certainpolychlorotrifluorethylene oils, generally ltnown commercially undersuch names as l luoro-flhem 208 or ltehF fluid, which possess lowviscosity with relatively high density. Such fluids, having density oithe order of L8 g./cc., permit a rotor mass of about lOO grains in afloat 2.5 inches in diameter and having a total weight of 240 grams.However, even if there is a disparity in the flotation provided by thefluid used, the hydro static bearing provides a centering force toprevent the float ill from bottoming, that is, coming into mechanicalcontact with the pad surfaces, even under the most severe accelerationalconditions. For example, assuming a latch of buoyancy of 4,6 grams,which at 1,060 gs accelerations] load becomes approximately 4.6ltilograrns, or it) pounds, the effective pressure difference requiredto support the sphere out of contact with the bearing pads is only 2psi.

Three circular coils hill, 82, and lid, lying in rectangular recesses inthe wall of the cavity Ell in the Xlt', X2 and Y2 planes, respectively,constitute an unlimited attitude picltoft' system for sensing thefloatorientation. liach coil winding in impregnated with an insulativematerial to provide rigidity. The coils hil lift and lid are supportedby ring Elli and screws dd in such a way that passages are provided oneither side of and behind the coils for the fluid to return from pads 32to outlet dd.

Referring now to Fit]. 2"), the float dill includes a thin sphericalshell hill of rigid, nonmagnetic material, such as beryllium, thatcompletely encloses an annular gyroscope rotor 92 and its drivingelements. The rotor $2 is supported for rotation about a spin axis ii,coinciding with a major diameter of the float, and has faces as and @ilsymmetrical with a plane till), lying normal to the spin axis 94 andpassing through a diameter of the float. For ease of assembly, the gyrorotor ilZ may be made of two parts Win and 5 212, symmetrical with, andjoined along the plane Mill. The parts 92a and Mb are formed of a heavy,nonmagnetic material, such as brass, and the outer surface of theassembled rotor is contoured to conform to the shell cur- VQTUI'B.

Disposed along the spin axis lid concentrically therewith, is a fixed,tubular axle lilo, its ends threadedly received in sup port blocltslllltl and Mill held, in turn, by dome-shaped, spaced segments lift andlid, respectively, which are formed on insulating material and haveouter surfaces contoured to precisely match the inner surface of theshell and suitably attached thereto. The rotor will has projectingannular flange portions illlti and lid. Attached to the outerextremities of the flanges llllti and lid are radially extending,annular rotor support plates lllll and i212, respectively, provided withaxial projecting hub portions HM and The internal surfaces of the hubs11%- and llfllti are raised (at Mill and will) to form the radiallyoutward races of duplex ball bearing arrangements which support therotor W3. for rotation about the axle Mill. The radi' ally inwardbearing races consist of split collars ll32 and Mid, securely mounted onthe axle lllllo, having circumferential, filleted depressions lilo andwill into which the outer races project. Axially spaced inner and outerball element sets Mil and M52, respectively, are retained between thedepressed collar portion ldtit and the raised outer race 12%; similarly,axially apaced inner and outer sets of ball elements lldd and Mo,respectively, are retained between the depressed collar portion lldiland the raised outer race llilll. Conventional single track ball orroller bearings require axial preloads to prevent unloading of one orthe other bearing during accelerations. hi the unloaded condition, theball or roller elements lite free of their tracks and thus cannotprovide any support to prevent radial displacement of the spin axis.With the arrangement! of the present invention, loads in either axialdirection are always sustained and transmitted by at least one set ofball elements on either side oi" the rotor llll. For example, with anacceleration force applied to the rotor parallel to the spin axis in thedirection indicated by the arrowhead on the axis M, the load is sharedby the ball element sets lldlll and Mid, whereas with an oppositelydirected acceleration force, the load is shared by the ball element setsM2 and M6. in contrast, conventional, single track rotor bearingsrequire preloads of at least onefourth of the maximum load duringacceleration to prevent bearing lift-off, while the duplex bearingarrangement employed herein does not require such preloads even for themost severe accelerational conditions. However, it may be desirable toprovide a light bearing preload to insure positive radial support of therotor under zero g conditions by inserting one or more shims of anappropriate: thickness between the elements forming the split collarsi318 and 1%.

The rotor is spun by a direct current motor which includes a permanentmagnet 11% carried within a central cavity formed in the rotor 92 and aplurality of fixed stator windings 115.2 arranged at equal intervalsabout the axle llllh. Preferably, the permanent magnet lldll is in theform of an annular ring and is made of high remanence magnetic material,such as Permalloy, shaped to fit an annular recess extending around thecentral opening in the rotor. The ring magnet lliill is magnetized so asto have its north and south poles diametrically opposed. Cylindricalmagnetic pole pieces lld l and 156, made of a low remanence magneticmaterial, such as cast i on, are mounted at the poles of the magnet i543and extend radially outward through openings formed between therotorhalves so that the pole tips terminate at the rotor periphery near theinterior surface of the spherical shell 9b. The magnetic flux of themagnet lldll is thus concentrated through the pole pieces i554 and 15band emerges from the pole tips at the rotor periphery to pass throughthe nonmagnetic shell 9d and cut the windings of the sensing coils hill,M and M as the rotor spins. To improve the efflciency and accuracy ofthe picltoff systems, the two hemispherical structures Zti and 2b aremade of a high permeability, high resistivity material, such as ferrite,to form a low reluctance magnetic path between the rotating pole pieces1M and 15th. This also shields the sensing coils till, 82 and b4 and thefloat lll from stray magnetic fields and to protect external circuitryfrom the rotating flux.

To permit full freedom of the float ill within the cavity 3t electricpower for the stator windings l52 during operation must be suppliedwithout external mechanical connections to the float dill. In theembodiment shown in H68. 3 and b-Q, this electrical operating currentfor the stator windings T52 is supplied by an arrangement ofrechargeable, disc-shaped battery cells use carried within the floatill. The batteries use are attached in circular arrays to both faces ofthe outer rims 16 i of a pair of insulating support members 1162disposed on either side of the rotor 92 symmetrical with the centralplane llllll and attached to the segments M2 and lid. The batteryterminals are connected to one another in an appropriate seriesparallelarrangement for providing the desired operating voltages, which aresupplied to the windings 152 along connecting leads lltih threadedthrough openings ms in the wall of the tubular axle roe.

Electrical current supplied to the stator windings 152 is distributed inthe desired direction of flow sequentially through the windings 152 by asuitable commutation system. The commutation system should have lowfriction drag and be free of loose fragments that might interfere withthe free rotation of the gyro rotor 92. Since considerable frictionexists between the brush contacts and the sliprings in conventionalmechani-' cal commutation systems and sizable fragments can be dislodgedby contact wear, an optical commutation system, such as illustrated inH65. 3 5, ti and 9, has been devised. Miniature light sources 1'72,1'73, mounted in apertures formed in the supports will, are arranged incircular patterns about the spin axis M on both sides of the rotorassembly. The light sources i172, 1173 may be individual bulbsgrain-ofwheat size, each aligned in a direction parallel to the spinaxis Wl with a corresponding stator winding 1152, or comprise a pair ofring-shaped fluorescent tubes, one disposed on each side of the rotor,mounted in the supports 162 concentric of the axis 94. Photocells 174,mounted on the windings 152 and having outputs connected thereto,respond to the light from the sources 172, 173 when the light passesthrough axially extending shutter openings 176, 177 formed in the rotorsupport plates 120 and 122, respectively. As the rotor 92 and itssupport plates 120 and 122 rotate, light from the source 172 passessequentially through the shutter opening 176 to successively energizeeach of the photocell elements 174 on one side of the rotor 92, whilelight from the source 173 passes through the shutter opening 177 tosuccessively energize the photocell elements 174 on the other side. Asthe light impinges on each photocell element 174, the current flow isgated, as will be more fully described later, in one direction or theother through windings 152 such that the polarity of the magnetic fieldproduced by the respective winding is approximately 90 displaced fromthe poles of the permanent magnet 150.

The gyro system of the present invention includes a caging mechanism 182primarily for maintaining initial alignment of the gyro spin axis 94prior to and during rotor runup. As shown in FIG. 2, the cagingmechanism 182 consists of a plurality of caging pins 184, contained, inthe retracted position, in the holes 186 in the hemispherical member 28.in the extended position, the pins 184 project into apertures 188 extending through the outer spherical shell into the interior of the float40 (FIG. 3). The caging pin apertures 188 each receive a spring loadedplunger 190 shaped at its lower end to fit snugly within the aperture188 and flush with the outer surface of the shell 90. Each plunger 190is slidably received within a bore 192 formed in the dome-shaped segment11 8 and has an inwardly extending, movable contact 194. When cagingpins 184 are inserted into the apertures 188, the plungers 190 movetoward stationary contact elements 196 in segment 114 against the actionof biasing springs 198 interposed between the plungers 190 andstationary contacts 196.

As shown in H0. 2, the reciprocating movement of the caging pins 184 canbe solenoid controlled. In the particular arrangement shown, the cag ngpins 184 are biased inwardly, that is, toward the cavity 30, by coilsprings 204. The shafts 206 of the pins 184 each extend outwardlythrough a guide aperture in the hemisphere structure 28. With the cagingpins retracted, each coil spring 204 is compressed between the enlargedhead of the corresponding pin 184 and the bottom of the bore 186. Theexpansion force of each spring 204 is in excess of the force exerted onthe plunger 1%) by the spring 198. The outer extremity of each shaft 206extends through a hole in a disc 210, which is secured to the inner endof a solenoid armature 212, and each shaft 206 is threaded to receive apair of locking nuts 214 adjustable along the length of the shaft. Thesolenoid armature 212 is actuated by a coil 215 and contains a pair ofV-shaped detent grooves that are yieldably engaged by a spring loadedball detent arrangement 218 to hold the armature in either an extendedor retracted position. With the armature 212 held in the outermostposition, the disc 210 acts on the locknuts 214, against the force ofthe springs 204 to hold the caging pins 184 flush with the wall of thecavity 30. When the solenoid coil 213 is energized to move the armature212 toward the cavity 30, the caging pins 184, under the influence ofsprings 204, move against the outer surface of the float 40. Then, whenthe tips of the caging pins 184 become aligned with the apertures 188,the stronger springs 204 overcome the force of the lighter coil springs198 and the pins 184 enter the float 40 causing movable contacts 194 tomake connection with the stationary contacts 196. The pins 184 and thereceiving apertures 188 are positioned so that in the caged position ofthe float 40, the spin axis 941 coincides with the reference ,axis XXand the plane 100 coincides with the reference axes Y! and 22.

The caging pins 184 also serve as a convenient means for establishingelectrical connections for supplying charging current to the batteries160 and operating power to the windings 152 during runup from anexternal power source (not shown), thereby preserving the limited powercapabilities of the batteries for operation when the rotor has reachedsteady state speed. For this purpose, each of the pins has an inner,conductive core 222 extending to the tip and surrounded by an insulatingsleeve 224. The core 222 is connected at the outer end to the externalsource by a lead wire 226 coupled to a sealed insulating terminal 228.The inner tip of the core 222 is exposed to make electrical contact withthe lower surface of the corresponding, conductive plunger 190. Thecontact 196 is connected to the batteries by appropriate electricalleads 230.

The float, and all its components, must, of course, form as nearly aspossible, a perfectly balanced unit to minimize acceleration sensitivedrift resulting from noncoincidence of the center of mass and thegeometric center. Imbalance can be compensated for by providingcounterweights 232, for example, suitably attached to the segment 112.

Referring now to FIG. 10, a battery charging and motor supply circuit,utilizing a four-pin caging mechanism, is depicted schematically. Forsimplicity of illustration, the caging mechanism has been shown inrectilinear fashion with the four caging pins 184a184d and thecorresponding receptacle plungers 190a-190d and contacts 196a-196dopposite one another across a gap 234 between the shell of the float 40and the inner surface of the hemisphere structure 28 defining thespherical cavity 30.

The caging pins mew-184d are shown in the retracted or uncaged positionwith their tips withdrawn to a position flush with the cavity-definingsurface and the plungers 190a-190d are held down by the force of thesprings Wish-198d to plug the apertures 188 in the shell 90. Two of thecaging pins 184a and 134d are connected by conductive leads directly tothe negative terminal of an appropriate external DC power supplies 236and 237. The other two caging pins 184d and 184s are similarly connectedby leads to the positive terminals of the power supplies 236 and 237.The plungers 1190b and 190d each have a conductive inner core surroundedby a layer of insulative material to insulate the core from theconductive shell 90, whereas the plungers 190a and 190d are not soinsulated so that when the caging pins are retracted, these plungersmake electrical contact with the conductive shell 90 to establish anelectrically conductive path between them. The plunger 190a is connectedto the negative terminal of the internal power supply, that is, thebatteries 160, the positive supply terminal of which is coupled to thecollector terminal of an NPN control transistor 238. The emitter oftransistor 23% is coupled to supply current to the stator windings 152of the rotor drive motor. The plunger 190d is connected to the otherside of the stator windings 152 and also through a Zener diode 240 tothe base of the transistor 238. A low valued resistor 2412, of the orderof ohms, connects the positive terminal of the battery power supply tothe base of the switching transistor 238, and together with the reverseconnected Zener diode 240 forms a voltage divider circuit whichestablishes a fixed bias potential at the base of the transistor 238.The plunger 1900 is coupled to the emitter terminal of the transistor238, while the remaining receptacle plunger 1911b is connected to thepositive terminal of the battery power supply 160.

In operation, with the caging pins 184a184d in the uncaged position,that is, out of contact with their respective receptacle plungers a190b,the battery power supply 160 is connected across the motor windings 152to provide current to be distributed by the optical brush system.Operating current from the positive terminal of the battery supply 160flows through the transistor 238 to the windings 152 and follows areturn path through the uninsulated receptible plungers 190a and 190d,connected by the conductive shell 90, to the negative terminal of thebattery supply 160. The transistor 238 conducts in an emitter followermode with its collectorto-base potential established at a fixed value bythe Zener diode 240 to maintain a constant voltage to the windings 152sustaining the desired spin rate.

0n the other hand, when the float 40 is caged by inserting the cagingpins 184a-1134d into their respective receptacles,

the plungers llhlla-Jlhlld are lifted free of contact with theconductive float shell 9i) and electrical contact is established betweenthe exterior and interior circuitry via the tips of the pinsHilda-Jlddd. With these contacts established, the battery power supplyloll within the float ll]! is connected across the external power supply2337 to receive charging current with its negative terminal coupled toan external ground potential through the plunger llllla caging pinllhda, and the dropping resistor 23% its positive terminal coupled tothe positive terminal of the external supply E37 through the pin limb,its associated plunger lliillb. The positive terminal of the externalsupply ass is also connected through the pin llh lc and plunger wilt: tothe emitter terminal of the transistor Mill and supplies operatingcurrent to the spin motor windings M2. The return path from the armaturewindings T53 is established through the pin llll ld and plunger Wild toground. Since the emitter of transistor 23% is maintained at a slightlyhigher potential than the bias potential established at its baseterminal by the volt age divider consisting of the resistor Edit and theZener diode Mil, the transistor ass is nonconductive during caging sothat the battery power supply litilll is effectively disconnected fromthe motor windings 1152.. Thus, the cells of the power supply lltill arecharged independently while operating current is supplied from theexternal source 2% to the motor for runup.

Separate external power supplies Sllllu are shown employed for chargingthe batteries lllili and for running the spin motor, rather than using asingle external supply, since battery charging usually requires a wellregulated high impedance source whereas quiclt starting is bestaccomplished by a low impedance source. However, the two supplies may beconsidered and in some cases actually be provided by a single externalsource.

In the form of the invention shown, employing an optical brush system,the current flow through each of the motor stator windings M32 iscontrolled in a given direction and with a selected timing by the actionof the photocells llld through appropriate switching circuitry. Anysuitable type of distribution circuit may be employed, but due to spaceand cost limitations, the circuit should employ as few elements aspossible and be relatively compact. For example, conventional gatedbridge circuits 2 each consisting of only four switching transistors orcontrolled rectifier-s, are employed. The input terminals of each bridgecircuit 2 M are connected across the DC power supply with thecorresponding winding ll52 connected across the output terminals. Thephotocells ll7d on one side of the stator, when energized, generate agating signal for one pair of the gating elements located in oppositelegs of the bridge circuit Md to produce current flow in the appropriatedirection through the windings l52, whereas the photocells i74 on theother side of the stator provide a gating signal, when energized, to thepair of gating elements in opposite legs to produce current flow throughthe windings M2 in the other direction. For simplicity, the details ofthese conventional circuit arrangements are not illustrated herein,since their implementation is easily within the capabilities of thoseskilled in basic electronics. Also, of course, it should be understoodthat where accuracy requirements permit the cost considerations areimportant, conventional low friction brush and slipring arrangements canbe employed instead of the optical brush arrangement to distributedriving power to the windings 1152.

Referring to Fit]. lilo, another form of power supply circuit ispreferred under high accelerations! conditions where simple voltagecontrol cannot maintain constant rotor speed because of changingfrictional loads. This circuit employs a separate speed sensing windingElllll electrically insulated from, but wound with, one of the statorwindings T52. The rotating magnet llll induces in the sensing windingEdd an alternating voltage signal with an amplitude indicative of therotor speed which is coupled through a diode sea, which eliminatesnegative half cycles, to a smoothing capacitor dil -l The positive DCvoltage developed across this smoothing capacitor 304 is applied as oneof the inputs to a voltage comparison circuit, such as the operationalamplifier 306, to be compared with a ill reference voltage indicative ofthe desired rotor speed. As shown, the reference voltage may be selectedby the setting of a potentiometer 308 connected across the internalpower supply 160. When the voltage across capacitor 31M reaches theamplitude of the reference voltage, the output from the operationalamplifier 3% is reduced and thus can be used to reduce the currentexcitation supplied to the windings 152 from the power source lull tomaintain the rotor 92 at constant speed. In the particular arrangementshown in FIG. llla, this is accomplished by supplying the output fromthe operational amplifier 35% through a diode 310 to the lamps W2. Thuswhen the rotor speed reaches the desired speed, the lamps 172 out oh sothat the commutator circuits no longer are switched to supply power tothe stator windings use. Alternatively, the output from the operationalamplifier 3% might be applied to control the flow of current to thecommutator circuits directly rather than being used to control the lamps1172. The rotor speed can be maintained constant even when variablefriction loading is experienced due to high accelerations.

Referring now to FIG. llll, there is schematically illustrated the rotor92, its spin axis lid and the pickoff, system including the threeorthogonally disposed sensing coils till, 32 and M and associated logiccircuitry. During rotor rotation, magnetic flux emanating from theopposite polarity pole pieces 154i and we carried by the rotor 92,periodically cuts the windings of the sensing coils till, $2 and M toproduce output signals indicative of the orientation of the gyro spinaxis with respect to the plane of each winding. Each time the fliix fromone of the pole pieces cuts the windings of one of the sensing coils,the amplitude of the output signal produced is proportional to the speedwith which the pole piece passes the windings. Ideally, with the rotorspin axis aligned perpendicular to the plane of one of the sensing coilsd2, $2 or M, no output signal would be generated in that coil becauseflux from the pole pieces does not cut across the windings but simplyrotates in the direction of the windings. l/llh the rotor spin axisslightly tilted from the axis perpendicular to the plane of the winding,only a small output signal is produced since the rate of flux variationcutting the windings is relatively small and takes place slowly.However, when the rotor spin axis lies in the plane of one of thesensing coils 82, $2. and M, the flux from the pole pieces ldd and llShcuts across the remaining windings at maximum speed and varies from zeroto its maximum and then back to zero in a relatively short time. Whenthe gyro spin axis is aligned approximately as shown in FIG. llll, thatis, tilted at 35l4iwith respect to each of the coil planes to passthrough the center of one of the triangular spherical segments definedbetween the coils, then the flux from "the pole pieces M4 and M6 cutseach of the sensing coils till, 82 and lid at approximately the samerate to produce output signals from each coil of approximately the sameamplitude. Therefore, assuming a constant spin rate, the amplitude ofthe output signal from each sensing coil is proportional to the sine ofthe angular displacement of the spin axis from the sensing coil axisnormal to the plane of the coil.

Accordingly, the output leads from the sensing coils can be coupled asseparate inputs to an analog signal analyzer and angle resolver 2'50 forgenerating output control signals for attitude control orinstrumentation use. The particular computation circuitry of the analogsignal analyzer and angle resolver is not described herein, since meansfor performing such computations are well known in the art. However, tocompensate for possible variations in spin rate, the amplitude of theoutput signals from each of the sensing coils should be compared againsta normalized signal amplitude that is indicative of the absolute spinrate. This is best accomplished in the analog signal analyzer and angleresolver 250 by computing a total vector amplitude S by the equation:

where a, b, and c are signal amplitudes from coils 82, 82 and d ll,respectively.

Using the total vector quantity S, the direction cosine for the angulardisplacement of the spin axis from each of the respective coil axeswould be computed by the equations:

iil n (5) where p, q, and r are the respective direction cosines. Thedirection cosine quantities computed are particularly useful in theoperation of signal attitude controls operated to control vehicleattitudes with respect to the sensing coil axes.

However, analysis of the output signals from the sensing coils 86, 82and 84 based upon amplitude alone is subject to positional ambiguitiesas to identical angular positions in opposite spherical quadrants. Also,pickoff measurements of angular position tend to be inaccurate for smallangular displacements between the spin axis and a sensing coil axis.This may be minimized by reducing the widths of the sensing coilsrelative to the area of the tips of the pole pieces 154 and 156, but theproblem remains.

Positional ambiguity resulting from amplitude measurements may beresolved by phase comparison of the output signals. With the rotor spinaxis 94 in different positional alignments with respect to the sensingcoils, the sequence with which the opposite polarity pole pieces 154 and156 pass the individual sensing coils is uniquely related to eachpossible position of the spin axis. Thus, the phase relationship betweenthe alternative output signals from the three sensing coils is uniquelyindicative of the spin axis alignment. Therefore, the output signalsfrom the three sensing coils can be coupled as inputs to phase detectorand comparison circuits 252, where the phase of each is established andcompared with the others. Outputs from the phase circuits 252,indicative of the phase relations, may then be used together with theoutputs from the analog signal analyzer and angle resolver 250, in anamplitude attitude reference computer 254 to determine the exact angularalignment of the rotor spin axis 94. When so used with outputs from theanalog signal analyzer and angle resolver 250, the outputs from thephase analyzer 252 need be nothing more than a relatively simple phasesequence indication that permits resolution of positional ambiguities.On the other hand, precise measurements of the sequence and phasedifference between the three signals can themselves be used to computeexact angular quantities of spin axis displacement in each of the threeorthogonal directions in an appropriate phase attitude referencecomputer 256. Moreover, by proper computational analysis of the waveshape or pulse duration produced, exact figures can be obtained for eventhe smallest angular displacements of the spin axis from the respectivesensing coil axis. Since the particular analyzer and computationcircuitry employed for performing these tasks would involve onlyconventional logic techniques and the details of these circuits will notconstitute a feature of this invention, these circuits will not beillustrated or described in detail herein. Typically, precise phasemeasurements may be obtained using conventional phase-lock techniques orthe like with the angular components of the spin axis displacement beingcomputed from the angular displacements measured between the phase ofthe three pickoff signals by conventional analog to digital computertechniques, such as are used in many prior art attitude referencesystems.

While most attitude reference systems used in ballistic missiles and thelike are required to operate for only a relatively a nd short timeperiod, certain applications particularly for aircraft and spacevehicles may require continued operation over extended periods. Thebatteries 160 carried within the float 40 can operate for onlyrelatively short periods. Accordingly, for extended operation, the powersupplied to run the spin motor must be derived from a source of greatercapacity which is external to the float 10, but without any physicalconnection between the float l0 and its surrounding apparatus.

Referring now to FIGS. 4 and 12-44, an alternative electrical energytransmission scheme is depicted. The float shell 260, instead of beingmade completely ofa conductive material, includes circular conductivesegments 262 at opposite poles which are centered, that is, symmetricalwith respect to the gyro spin axis 94 and separated from each other byan intermediate portion 264 of the shell, which portion is formed of anonconductive, insulative material. The circular conductive segments 262have an included angle of and are centered with respect to spin axis 94(for clarity, only two of the eight bearing pads are shown in FIG. 13).The bearing pads 266 are made of conductive material and areelectrically connected through a suitable power gating circuit 268 toreceive operating power from an appropriate AC source 270. The gatingcircuit 268 receives gaging control signals from an attitude referencecomputer, such as 254 or 256 in FIG. 1 l, indicative of theinstantaneous angular position of the gyro spin axis, which, in turn,determines the particular bearing pads 266 that are immediately adjacentthe conductive segments 262.

In the arrangement of FIGS. 12-14, a relatively high frequencyalternating current power signal, for example, volts at l mHz, fromsource 270 is supplied to one or more pairs of bearing pads 266 onopposite sides of the float that overlie the conductive segments 262.The bearing fluid is nonconductive with good dielectric properties sothat the high frequency alternating current is thus transferred from thebearing pads 266 across the gap 272 (between the shell 260 and bearingpads 266) to the segments 262 by capacitive coupling. Within the float40, as shown in FIG. 14, the conductive segments 262 are connected toopposite input terminals of a full wave rectifier circuit 274 thatconverts the high frequency AC to a DC signal for driving the DC spinmotor.

Alternatively, as shown in FIG. 15, the alternating current signalwithin the float derived across the capacitive gap 272:: may be used todrive an appropriate AC spin motor. In this case, there is no need for abrush system, but the high frequency signal necessary for achievingefficient power transfer through the capacitive coupling to the floatwould be applied through a frequency dividing circuit 276 to reduce thefrequency to a value suitable for driving the AC motor.

As a further alternative, shown by the broken lines in FIG. 13, with theuse of an appropriate conductive flotation fluid, DC power from anexternal source 278 may be applied to the float through opposite pathsof bearing pads 266 overlying the conductive circular segments 262. Thismethod of power transfer, however, is relatively inefficient because ofpower leakage around the float through the conductive flotation fluid.Efficiency is maximized if the resistivity of the conductive fluid ishigh enough to ensure that the resistance through the conductive fluidbetween opposite bearing pads 266 is high relative to the totalresistance of the path directly across the gap from the bearing pads 266to the conductive segments 262 and through the spin motor statorwindings 152.

Referring now to FIG. 16, an all-attitude gyro reference system isprovided, including two full-freedom gyro systems 280 and 282, inaccordance with the invention, with their spin axes 284 and 286,respectively, initially 90 apart. A mounting means 288 supports the gyrosystems. In accordance with the usual practice, the gyro spin axes 284and 286 are aligned perpendicular to the roll axis of the system andparallel to the pitch and yaw axes, respectively. The outputs of the twogyro systems can then be processed by a conventional signal conditioner290 which transforms the gyro pickoff outputs to pitch, yaw and rollattitude signals, which are measured in vehicle coordinates forconvenient use in the vehicle instrumentation and attitude controlsystems.

In systems where the gyros, after use, are to be recaged for lateroperation, the float 40 must be returned to its upright position topermit insertion of the caging pins 184 into the apertures 188 in thefloat. The float 40 is most easily restored to its upright position byshorting the windings of the sensing coil hi), the axis of whichcorresponds to the desired initial alignment of the spin axis 9d.Usually, after a series of maneuvets over a period of time, the spinaxis will be only slightly misaligned due to viscous drag on the surfaceof the float, so that the gyro does not return exactly to its initialalignment even though the system is returned to its exact starting pointin inertial space. Such misalignments are normally very small comparedto the alignment errors resulting from gimbal bearing friction inconventional gyros, and the errors themselves are predictable and easilycompensated since there are no coulomb friction discontinuities andhysteresis. Therefore, assuming that this misalignment does not exceed90 from the axis of the coil shorting the coil windings, as shown inFIG. lll, by means of a simple switch 1M2, resuits in relatively largecurrents being induced in the windings by the flux from the rotatingpole pieces rsir and llfiti. The current flow induced in the coil ddproduces a magnetic field through the coil that applies a restoringtorque to the rotor 92 tending to align the plane of rotation of thepole pieces llfid and Mid with the plane of the coil, which representsthe lowest energy condition of the system. Since the applied torquingforce on the rotor 92 is directly towards the desired alignment,precession of the spin axis 9d is generally in a direction normal to thedirect path for realignment so that the spin axis spirals inward untilit reaches the desired alignment with the coil axis.

To achieve faster alignment, alternating currents might be applied tothe coil in such a phase relationship that the float would be torqued byeddy currents in a shell hill in the manner of an induction motor, thespin axis 9d to precess directly towards axis XX. Other means ofobtaining float realignment might involve the use of pneumatic jetsapplied to the float surface at various points as necessary, based uponthe known alignment of the spin axis.

What I claim is:

l. A gyroscope system comprising:

a body defining a spherical cavity;

a spherical, hollow float disposed within said cavity;

a gyroscope rotor within said float, journaled for rotation about aselected spin axis through the center of said float; driving meanscontained within said float for rotating said rotor;

a support system including a relatively low viscosity flotation fluidhaving a density of approximately the same density as said float andcompletely surrounding said float within said cavity to maintain theouter surface of said float out of mechanical contact with said body;

energy radiating means carried for rotation at the periphery of saidrotor, said float being permeable to the energy radiated; and,

sensing means attached to said body and responsive to the energyradiated from the rotor for generating output signals indicative of theorientation of said spin axis with respect to said body.

2. The gyroscope system of claim ll wherein:

said energy radiating means consists of diametrically opposed magneticpole pieces of opposite polarity for radiating a magnetic field from theperiphery of said rotor, said float being ofa nonmagnetic material; and,

said sensing means comprises three magnetic field sensing coils mountedwithin said cavity to encircle said float, each said coil lyingsubstantially in a plane mutually orthogonal with respect to the planesof the other coils, and each said coil having a central axis extendingperpendicular to the plane of said coil.

3. The gyroscope system of claim 2. wherein:

said flotation system further includes a plurality of hydrostaticbearing pads defining the interior of said cavity, each having aspherical bearing surface corresponding substantially to the quadraturespherical segment defined between the orthogonally arranged sensingcoils.

The gyroscope system of claim 2 further comprising:

circuit means connected to receive said output signals from each of saidsensing coils and responsive to the amplitude of said output signals forgenerating directional outputs indicative of the angular displacement ofsaid spin axis of the float from each of said coil axes.

5. The gyroscope system of claim 2 further comprising:

circuit means connected to receive said output signals from each of saidsensing coils for detecting the phase of each of said output signals andthe relative phase sequence of the output signals from each of saidsensing coils; and,

means responsive to the differences in phase and the detected phasesequence for providing directional outputs indicative of the angulardisplacement of said spin axis from each of said coil axes.

6; The gyros cope system of claim 2 further comprising:

circuit means connected to receive the output signals from each of saidsensing coils and responsive to said output signals for generatingdirectional outputs indicative of the angular displacement of said spinaxis from each of said coil axes.

7. The gyroscope system of claim 1 wherein:

said driving means includes a direct current motor powered by batterymeans carried within said float.

h. The gyroscope system ofclaim '7 wherein said motor includes agenerally cylindrical stator comprising a plurality of windings, saidstator being mounted concentric of said spin axis;

a generally cylindrical, permanent magnet rotor having a central,concentric opening for receiving said stator, said rotor being journaledfor rotation about said stator concentrically therewith; and,

an optical brush system comprising light source means disposed aboutsaid spin axis adjacent said rotor, at plurality of photocell means eachassociated with one of said stator windings and disposed about said spinaxis to be selectively activated by said light source for providingcurrent flow in a given direction through the associated armaturewinding, and optical shutter means carried by said rotor and interposedbetween said light source means and said photocell means for selectivelyactivating each of said photocell circuits in synchronization with therotation of said rotor.

9.The gyroscope system of claim 3 further comprising:

a source of electrical power external to said spherical cavifirst andsecond conductive segments forming the spherical exterior surface ofsaid float at opposite ends of said spin axis, each of said bearing padshaving a conductive surface adjacent said float;

gating means responsive to said coil outputs for selectively providingelectrical power from said source to the oppositely disposed pairs ofsaid bearing pads having their conductive surface immediately adjacentsaid conductive segments on said float, said electrical power beingtransferred from the surface of said bearing pads to the conductivesegments on said float; and, in which:

said rotor driving means includes a motor means and a power controlcircuit within said float connected to said conductive segments tosupply the transferred electrical power to said motor.

10. The gyroscope system of claim 9 wherein:

said external source of electrical power is a high frequency alternatingcurrent source;

said motor in a direct current motor;

said power control circuit includes a rectifier circuit connectedbetween said conductive segments to rectify the high frequencyalternating current transferred from said bearing pads to provide directcurrent for driving said motor; and,

said flotation fluid is a nonconductive insulative liquid having gooddielectric properties.

111. The gyroscope system of claim 9 wherein:

said external source of electrical power constitutes a high frequencyalternating current source;

said motor is an alternating current motor operating at a relatively lowfrequency;

said power control circuit includes a frequency divider circuitconnected to said conductive segments to receive the high frequencyalternating current power transferred from said selected bearing padsand for providing relatively low frequency alternating current foroperating said motor; and,

said flotation fluid is a nonconductive insulative fluid having gooddielectric properties.

12. The gyroscope system of claim 9 wherein:

said external electrical supply source is a source of direct current;

said flotation fluid is conductive but has a relatively lowconductivity;

said motor is a direct current motor; and,

said power control circuit includes a voltage regulator circuitconnected to said conductive segments for supplying the direct currentpower transferred from said bearing pads at a predetermined voltage todrive said motor.

13. A gyroscope system for use in high accelerational environmentscomprising:

a body defining a spherical cavity;

a spherical, hollow float disposed within said cavity;

a flotation system including a flotation fluid for supporting saidspherical float out of mechanical contact with said body and withapproximately zero buoyancy for free rotational movement within saidcavity;

a gyro rotor having a spin axis;

means for rotatably supporting said gyro rotor within said float withits spin axis extending -along an axis of said float;

drive means contained within said float for rotating said rotor; and,

means attached to said body within said spherical cavity and responsiveto the rotation of said rotor for sensing the angular position of saidspin axis relative to selected axes of said body structure.

14. The gyro system of claim 13 in which:

said means for rotatably supporting said gyro rotor includessymmetrically disposed, axially extending hub portions on opposite endsof said rotor, an axle fixedly mounted within said float along saidfloat axis, and duplex bearings spaced equidistant from a plane ofsymmetry perpendicular to said float axis for supporting said rotor,each said duplex bearing including a radially outer race comprising afilleted projection on said hub directed radially inwardly, a radiallyinner race comprising a split collar mounted on said axle and having acircumferential, cupshaped depression into which said outer raceextends; and, axially inner and outer sets of ball elements interposedbetween said outer race and said inner race, said split collar adaptedto be axially shimmed for preloading said bearing.

15. The gyro system of claim 33 further comprising:

a plurality of hydrostatic bearing pads affixed to said body structurewithin said cavity and providing spherical bearing surfaces conformingto spherical segments of the exterior surface of said float; and,

means within said body structure for delivering said flotation fluidunder pressure through a central opening in the bearing surface of saidbearing pads to thereby support the exterior surface of said float.

16. The gyro system of claim 13 further comprising:

a caging apparatus consisting of a plurality of caging pins mountedwithin said body structure for reciprocal movement toward and away fromsaid spherical cavity;

said float including a plurality of caging pin receptacles formed insaid float for receiving said caging pins; and,

means for reciprocally moving said caging pins to selectively insertthem within said receptacles to hold said float with its selected axisaligned with a predetermined axis of the body structure to preventrotation of said float during acceleration of said rotor to the desiredspin rate.

17. The gyro system of claim 16 wherein:

said driving means includes a DC spin motor disposed within said float,said motor including a permanent magnet carried by said rotor and aplurality of stator windings mounted within said float in operativerelation with said permanent magnet, and power supply means consistingof a plurality of battery cells mounted within said float to supplyoperating power to said stator windings. 18. The gyro system of claim 17further comprising: means for supplying direct current from a sourceexternal to said float connected to said plurality of caging pins, saidcaging pins each having a conductive core for coupling said directcurrent power to the tip, said caging pin receptacles in said floathaving means for selectively contacting the tips of said caging pins tocouple said direct current power from the external source to said statorwindings for supplying operating power during acceleration of said rotorto the desired spin rate; and, circuit means connected between saidbattery cells and said stator windings for disconnecting said batterycells from said stator windings whenever the caging pins are insertedand for permitting the flow of operating current from said battery cellsto said stator windings when the caging pins are withdrawn from thecaging pin receptacles. 19. A gyroscope reference system comprising: apair of gyroscope systems, each gyroscope system including: a bodydefining a spherical cavity; a spherical float disposed within saidcavity; hydrostatic bearing means for suspending said float within saidcavity completely out of mechanical contact with said body; gyro rotormeans mounted for rotation within said float about an axis fixed withrespect to said float; means contained within said float for rotatablydriving said motor; and,

three dimensional pickoff means attached to said bodyand cooperatingwith said float for sensing the attitude of said float relative to saidbody;

means for mounting said pair of gyroscope systems; and,

signal conditioning means responsive to said pickoff means of said pairof gyroscope systems and having outputs representing the angulardisplacement of selected axes of said mounting means from referenceaxes.

20. An all-attitude reference system for use in a vehicle, said vehiclehaving pitch, yaw and roll axes, comprising:

a pair of gyro systems, each system including:

a body defining a cavity; a spherical float disposed within said cavity;hydrostatic bearing means for suspending said float within said cavitycompletely out of mechanical contact with said body; gyro rotor meansmounted for rotation within said float about a spin axis fixed withrespect to said float, said rotor carrying magnet means generating amagnetic flux, said float being permeable to said flux; pickoff meansincluding three mutually orthogonal planar coils attached to said bodyabout said cavity, each said coil producing an electrical signal whencut by said flux during rotor rotation, said pickoff means havingoutputs; and, caging means carried by said body, said caging means beingselectively actuatable to engage and hold said float in fixed relationto said body; means for fixedly supporting said bodies of said pair ofgyro systems in said vehicle with the planes of said coils of said coilsof one gyro system parallel to the planes of the coils of the other gyrosystem, said coils having a known orientation with respect to saidvehicle pitch, yaw and roll axes; and, signal conditioning meansresponsive to the outputs of said coils, said signal conditioning meansincluding means for providing output signals representing the angulardeviation of said vehicle pitch. yaw and roll axes from a set ofreferences axes, said caging means being operable to preset the spinaxes of said rotors at a known angular relation with each other and thereference axes.

21. A gyro system comprising:

a body defining a cavity;

a float disposed within said cavity;

means for suspending said float within said cavity to permit completerotational freedom of said float relative to said body;

gyro rotor means mounted for rotation within said float about a spinaxis fixed with respect to said float;

means contained within said float for rotatably driving said rotor; and,

means attached to said body and cooperating with said float for sensingthe attitude of said float relative to said body.

22. A gyro system, as defined in claim 211, in which:

said attitude sensing means includes inductor means at tached to saidbody, said rotor including magnet means for inducing a current in saidinductor during rotation of said rotor.

23. A gyro system, as defined in claim Ell, in which:

said rotor driving means includes a motor powered by electrical cellmeans.

24. A gyro comprising a float suspended in a fluid completelysurrounding said float and contained within a body, said float havingcomplete rotational freedom within said body, said float housing a gyrorotor having a spin axis fixed with respect to said float and meansoperatively associated with said rotor for driving said rotor, whereby,during rotation of said rotor, said float remains fixed in inertialspace with respect to said body, irrespective of the position of saidbody relative to said float, said gyro further including sensing meansattached to said body for sensing the relative orientation of said bodyand said float.

25. The gyroscope system of claim ll wherein said driving meanscomprises:

an electric motor;

a power supply source; and,

circuit means responsive to the rotational speed of said rotor forcontrolling the amount of electric power supplied by said source todrive said motor and maintain said rotor at a desired rotational speed.

26. The gyroscope system of claim 25 wherein said circuit meanscomprises:

a sensing coil disposed within said electrical motor for generating aspeed signal having an amplitude proportional to the rotational speed ofsaid rotor;

means coupled to said power supply for generating a reference signalhaving an amplitude indicative of the desired rotational speed;

comparison means for comparing the amplitudes of said speed signal andsaid reference signal to generate an output signal indicative of theamplitude difference; and, control means responsive to the output signalfor reducing the flow of electrical power from said power supply meansto said electric motor as the rotor approaches said desired rotationalspeed.

27. The gyroscope system of claim 26 wherein: said electrical motor is adirect current motor including magnetic poles carried by said rotor, aplurality of stator windings disposed within said rotor adjacent saidmagnetic poles, and an optical commutation system including light sourcemeans operated by power from said supply source, photocell circuitsresponsive to the impingement of light from said light source means forselectively gating electrical power from said power supply means to saidstator windings, and an optical shutter means carried by said rotor forenergizing said photocell circuits in synchronization with the rotationof said rotor; and,

said control means comprises means for connecting said output signalfrom said comparison means to vary the application of operating power tosaid li ht source means, whereby the light produced by said lig t sourcemeans is celeration loads comprising:

a gyro rotor;

a direct current electrical motor for driving said rotor includingopposite magnetic poles carried by said rotor and a plurality of statorwindings disposed within said rotor adjacent said magnetic poles, and acommutation system for selectively distributing operating power to saidstator windings in synchronization with the rotation of said rotor;

a sensing winding disposed adjacent said stator windings for generatinga speed signal having an amplitude indicative of the rotational speed ofsaid rotor; and,

control means responsive to said speed signal for reducing the operatingpower applied to said stator windings as the rotational speed of saidrotor approaches a desired speed.

29. The gyroscope system of claim 28 wherein:

said commutation system is an optical system having light source means,photocell circuits responsive to the impingement of light from saidlight source means for selectively gating electrical power to saidstator winding to drive said rotor, an optical shutter means carried forrotation by said rotor for energizing said photocell circuits insynchronization with the rotation of said rotor; and,

control means responsive to said speed signal for reducing operatingpower supplied to said light source means whereby the light impingingupon said photocell circuits is reduced as said rotor approaches adesired speed.

30. The gyroscope system of claim 28 wherein said control meanscomprises:

means for establishing a reference signal with an amplitude indicativeof the desired rotational speed of the rotor;

a comparison circuit for comparing the amplitudes of said speed signaland said reference signal to produce an output voltage indicative of theamplitude difference; and,

means coupling said output signal to vary the power supplied to saidlight source means.

1. A gyroscope system comprising: a body defining a spherical cavity; aspherical, hollow float disposed within said cavity; a gyroscope rotorwithin said float, journaled for rotation about a selected spin axisthrough the center of said float; driving means contained within saidfloat for rotating said rotor; a support system including a relativelylow viscosity flotation fluid having a density of approximately the samedensity as said float and completely surrounding said float within saidcavity to maintain the outer surface of said float out of mechanicalcontact with said body; energy radiating means carried for rotation atthe periphery of said rotor, said float being permeable to the energyradiated; and, sensing means attached to said body and responsive to theenergy radiated from the rotor for generating output signals indicativeof the orientation of said spin axis with respect to said body.
 2. Thegyroscope system of claim 1 wherein: said energy radiating meansconsists of diametrically opposed magnetic pole pieces of oppositepolarity for radiating a magnetic field from the periphery of saidrotor, said float being of a nonmagnetic material; and, said sensingmeans comprises three magnetic field sensing coils mounted within saidcavity to encircle said float, each said coil lying substantially in aplane mutually orthogonal with respect to the planes of the other coils,and each said coil having a central axis extending perpendicular to theplane of said coil.
 3. The gyroscope system of claim 2 wherein: saidflotation system further includes a plurality of hydrostatic bearingpads defining the interior of said cavity, each having a sphericalbearing surface corresponding substantially to the quadrature sphericalsegment defined between the orthogonally arranged sensing coils.
 4. Thegyroscope system of claim 2 further comprising: circuit means connectedto receive said output signals from each of said sensing coils andresponsive to the amplitude of said output signals for generatingdirectional outputs indicative of the angular displacement of said spinaxis of the float from each of said coil axes.
 5. The gyroscope systemof claim 2 further comprising: circuit means connected to receive saidoutput signals from each of said sensing coils for detecting the phaseof each of said output signals and the relative phase sequence of theoutput signals from each of said sensing coils; and, means responsive tothe differences in phase and the detected phase sequence for providingdirectional outputs indicative of the angular displacement of said spinaxis from each of said coil axes.
 6. The gyroscope system of claim 2further comprising: circuit means connected to receive the outputsignals from each of said sensing coils and responsive to said outputsignals for generating directional outputs indicative of the angulardisplacement of said spin axis from each of said coil axes.
 7. Thegyroscope system of claim 1 wherein: said driving means includes adirect current motor powered by battery means carried within said float.8. The gyroscope system of claim 7 wherein: said motor includes agenerally cylindrical stator comprising a plurality of windings, saidstator being mounted concentric of said spin axis; a generallycylindrical, permanent magnet rotor having a central, concentric openingfor receiving said stator, said rotor being journaled for rotation aboutsaid stator concentrically therewith; and, an optical brush systemcomprising light source means disposed about said spin axis adjacentsaid rotor, a plurality of photocell means each associated with one ofsaid stator windings and disposed about said spin axis to be selectivelyactivated by said light source for providing current flow in a givendirection through the associated armature winding, and optical shuttermeans carried by said rotor and interposed between said light sourcemeans and said photocell means for selectively activating each of saidphotocell circuits in synchronization with the rotation of said rotor.9. The gyroscope system of claim 3 further comprising: a source ofelectrical power external to said spherical cavity; first and secondconductive segments forming the spherical exterior surface of said floatat opposite ends of said spin axis, each of said bearing pads having aconductive surface adjacent said float; gating means responsive to saidcoil outputs for selectively providing electrical power from said sourceto the oppositely disposed pairs of said bearing pads having theirconductive surface immediately adjacent said conductive segments on saidfloat, said electrical power being transferred from the surface of saidbearing pads to the conductive segments on said float; and, in which:said rotor driving means includes a motor meaNs and a power controlcircuit within said float connected to said conductive segments tosupply the transferred electrical power to said motor.
 10. The gyroscopesystem of claim 9 wherein: said external source of electrical power is ahigh frequency alternating current source; said motor in a directcurrent motor; said power control circuit includes a rectifier circuitconnected between said conductive segments to rectify the high frequencyalternating current transferred from said bearing pads to provide directcurrent for driving said motor; and, said flotation fluid is anonconductive insulative liquid having good dielectric properties. 11.The gyroscope system of claim 9 wherein: said external source ofelectrical power constitutes a high frequency alternating currentsource; said motor is an alternating current motor operating at arelatively low frequency; said power control circuit includes afrequency divider circuit connected to said conductive segments toreceive the high frequency alternating current power transferred fromsaid selected bearing pads and for providing relatively low frequencyalternating current for operating said motor; and, said flotation fluidis a nonconductive insulative fluid having good dielectric properties.12. The gyroscope system of claim 9 wherein: said external electricalsupply source is a source of direct current; said flotation fluid isconductive but has a relatively low conductivity; said motor is a directcurrent motor; and, said power control circuit includes a voltageregulator circuit connected to said conductive segments for supplyingthe direct current power transferred from said bearing pads at apredetermined voltage to drive said motor.
 13. A gyroscope system foruse in high accelerational environments comprising: a body defining aspherical cavity; a spherical, hollow float disposed within said cavity;a flotation system including a flotation fluid for supporting saidspherical float out of mechanical contact with said body and withapproximately zero buoyancy for free rotational movement within saidcavity; a gyro rotor having a spin axis; means for rotatably supportingsaid gyro rotor within said float with its spin axis extending along anaxis of said float; drive means contained within said float for rotatingsaid rotor; and, means attached to said body within said sphericalcavity and responsive to the rotation of said rotor for sensing theangular position of said spin axis relative to selected axes of saidbody structure.
 14. The gyro system of claim 13 in which: said means forrotatably supporting said gyro rotor includes symmetrically disposed,axially extending hub portions on opposite ends of said rotor, an axlefixedly mounted within said float along said float axis, and duplexbearings spaced equidistant from a plane of symmetry perpendicular tosaid float axis for supporting said rotor, each said duplex bearingincluding a radially outer race comprising a filleted projection on saidhub directed radially inwardly, a radially inner race comprising a splitcollar mounted on said axle and having a circumferential, cup-shapeddepression into which said outer race extends; and, axially inner andouter sets of ball elements interposed between said outer race and saidinner race, said split collar adapted to be axially shimmed forpreloading said bearing.
 15. The gyro system of claim 13 furthercomprising: a plurality of hydrostatic bearing pads affixed to said bodystructure within said cavity and providing spherical bearing surfacesconforming to spherical segments of the exterior surface of said float;and, means within said body structure for delivering said flotationfluid under pressure through a central opening in the bearing surface ofsaid bearing pads to thereby support the exterior surface of said float.16. The gyro system of claim 13 further comprising: A caging apparatusconsisting of a plurality of caging pins mounted within said bodystructure for reciprocal movement toward and away from said sphericalcavity; said float including a plurality of caging pin receptaclesformed in said float for receiving said caging pins; and, means forreciprocally moving said caging pins to selectively insert them withinsaid receptacles to hold said float with its selected axis aligned witha predetermined axis of the body structure to prevent rotation of saidfloat during acceleration of said rotor to the desired spin rate. 17.The gyro system of claim 16 wherein: said driving means includes a DCspin motor disposed within said float, said motor including a permanentmagnet carried by said rotor and a plurality of stator windings mountedwithin said float in operative relation with said permanent magnet, andpower supply means consisting of a plurality of battery cells mountedwithin said float to supply operating power to said stator windings. 18.The gyro system of claim 17 further comprising: means for supplyingdirect current from a source external to said float connected to saidplurality of caging pins, said caging pins each having a conductive corefor coupling said direct current power to the tip, said caging pinreceptacles in said float having means for selectively contacting thetips of said caging pins to couple said direct current power from theexternal source to said stator windings for supplying operating powerduring acceleration of said rotor to the desired spin rate; and, circuitmeans connected between said battery cells and said stator windings fordisconnecting said battery cells from said stator windings whenever thecaging pins are inserted and for permitting the flow of operatingcurrent from said battery cells to said stator windings when the cagingpins are withdrawn from the caging pin receptacles.
 19. A gyroscopereference system comprising: a pair of gyroscope systems, each gyroscopesystem including: a body defining a spherical cavity; a spherical floatdisposed within said cavity; hydrostatic bearing means for suspendingsaid float within said cavity completely out of mechanical contact withsaid body; gyro rotor means mounted for rotation within said float aboutan axis fixed with respect to said float; means contained within saidfloat for rotatably driving said motor; and, three dimensional pickoffmeans attached to said body and cooperating with said float for sensingthe attitude of said float relative to said body; means for mountingsaid pair of gyroscope systems; and, signal conditioning meansresponsive to said pickoff means of said pair of gyroscope systems andhaving outputs representing the angular displacement of selected axes ofsaid mounting means from reference axes.
 20. An all-attitude referencesystem for use in a vehicle, said vehicle having pitch, yaw and rollaxes, comprising: a pair of gyro systems, each system including: a bodydefining a cavity; a spherical float disposed within said cavity;hydrostatic bearing means for suspending said float within said cavitycompletely out of mechanical contact with said body; gyro rotor meansmounted for rotation within said float about a spin axis fixed withrespect to said float, said rotor carrying magnet means generating amagnetic flux, said float being permeable to said flux; pickoff meansincluding three mutually orthogonal planar coils attached to said bodyabout said cavity, each said coil producing an electrical signal whencut by said flux during rotor rotation, said pickoff means havingoutputs; and, caging means carried by said body, said caging means beingselectively actuatable to engage and hold said float in fixed relationto said body; means for fixedly supporting said bodies of said pair ofgyro systems in said vehicle with the planes of said coils of said coilsof one gyro system parallel to the planeS of the coils of the other gyrosystem, said coils having a known orientation with respect to saidvehicle pitch, yaw and roll axes; and, signal conditioning meansresponsive to the outputs of said coils, said signal conditioning meansincluding means for providing output signals representing the angulardeviation of said vehicle pitch, yaw and roll axes from a set ofreferences axes, said caging means being operable to preset the spinaxes of said rotors at a known angular relation with each other and thereference axes.
 21. A gyro system comprising: a body defining a cavity;a float disposed within said cavity; means for suspending said floatwithin said cavity to permit complete rotational freedom of said floatrelative to said body; gyro rotor means mounted for rotation within saidfloat about a spin axis fixed with respect to said float; meanscontained within said float for rotatably driving said rotor; and, meansattached to said body and cooperating with said float for sensing theattitude of said float relative to said body.
 22. A gyro system, asdefined in claim 21, in which: said attitude sensing means includesinductor means attached to said body, said rotor including magnet meansfor inducing a current in said inductor during rotation of said rotor.23. A gyro system, as defined in claim 21, in which: said rotor drivingmeans includes a motor powered by electrical cell means.
 24. A gyrocomprising a float suspended in a fluid completely surrounding saidfloat and contained within a body, said float having complete rotationalfreedom within said body, said float housing a gyro rotor having a spinaxis fixed with respect to said float and means operatively associatedwith said rotor for driving said rotor, whereby, during rotation of saidrotor, said float remains fixed in inertial space with respect to saidbody, irrespective of the position of said body relative to said float,said gyro further including sensing means attached to said body forsensing the relative orientation of said body and said float.
 25. Thegyroscope system of claim 1 wherein said driving means comprises: anelectric motor; a power supply source; and, circuit means responsive tothe rotational speed of said rotor for controlling the amount ofelectric power supplied by said source to drive said motor and maintainsaid rotor at a desired rotational speed.
 26. The gyroscope system ofclaim 25 wherein said circuit means comprises: a sensing coil disposedwithin said electrical motor for generating a speed signal having anamplitude proportional to the rotational speed of said rotor; meanscoupled to said power supply for generating a reference signal having anamplitude indicative of the desired rotational speed; comparison meansfor comparing the amplitudes of said speed signal and said referencesignal to generate an output signal indicative of the amplitudedifference; and, control means responsive to the output signal forreducing the flow of electrical power from said power supply means tosaid electric motor as the rotor approaches said desired rotationalspeed.
 27. The gyroscope system of claim 26 wherein: said electricalmotor is a direct current motor including magnetic poles carried by saidrotor, a plurality of stator windings disposed within said rotoradjacent said magnetic poles, and an optical commutation systemincluding light source means operated by power from said supply source,photocell circuits responsive to the impingement of light from saidlight source means for selectively gating electrical power from saidpower supply means to said stator windings, and an optical shutter meanscarried by said rotor for energizing said photocell circuits insynchronization with the rotation of said rotor; and, said control meanscomprises means for connecting said output signal from said comparisonmeans to vary the application of operating power to said light sourcEmeans, whereby the light produced by said light source means is reducedas the rotational speed of said rotor approaches said desired speed. 28.A gyroscope system for operation under varying acceleration loadscomprising: a gyro rotor; a direct current electrical motor for drivingsaid rotor including opposite magnetic poles carried by said rotor and aplurality of stator windings disposed within said rotor adjacent saidmagnetic poles, and a commutation system for selectively distributingoperating power to said stator windings in synchronization with therotation of said rotor; a sensing winding disposed adjacent said statorwindings for generating a speed signal having an amplitude indicative ofthe rotational speed of said rotor; and, control means responsive tosaid speed signal for reducing the operating power applied to saidstator windings as the rotational speed of said rotor approaches adesired speed.
 29. The gyroscope system of claim 28 wherein: saidcommutation system is an optical system having light source means,photocell circuits responsive to the impingement of light from saidlight source means for selectively gating electrical power to saidstator winding to drive said rotor, an optical shutter means carried forrotation by said rotor for energizing said photocell circuits insynchronization with the rotation of said rotor; and, control meansresponsive to said speed signal for reducing operating power supplied tosaid light source means whereby the light impinging upon said photocellcircuits is reduced as said rotor approaches a desired speed.
 30. Thegyroscope system of claim 28 wherein said control means comprises: meansfor establishing a reference signal with an amplitude indicative of thedesired rotational speed of the rotor; a comparison circuit forcomparing the amplitudes of said speed signal and said reference signalto produce an output voltage indicative of the amplitude difference;and, means coupling said output signal to vary the power supplied tosaid light source means.